In HVAC systems (heating, ventilating, air conditioning), conditioned supply air discharged from a blower is often conveyed to various rooms or areas within a building by way of ductwork. Conventional ductwork is typically formed of sheet metal and is often installed above ceilings for convenience and aesthetics. But in warehouses, manufacturing plants and many other buildings, the ducts are suspended below the ceiling and are thus exposed.
Many problems associated with exposed metal ducts are overcome by the use of fabric ducts, such as DUCTSOX® fabric ducts by Frommelt Safety Products Corporation of Milwaukee, Wis. Such ducts typically have a fabric wall that is air-permeable to broadly and evenly disperse the air into the room being conditioned or ventilated. If greater airflow is needed in certain areas, the fabric duct can be provided with additional discharge openings, such as air registers or cutouts in the fabric. Example fabric air ducts and discharge openings are disclosed in U.S. Pat. Nos. 6,958,011 and 6,960,130; which are specifically incorporated by reference herein.